The field of the invention relates generally to rotary machines and, more particularly, to nozzle assemblies for use in a rotary machine.
At least some rotary machines, such as known steam turbine engines, include a defined steam path. The path includes, in serial-flow relationship, a steam inlet, a turbine, and a steam outlet. Many of known steam turbine engines include stationary nozzles that channel a flow of steam towards rotating buckets or turbine blades. The nozzles and rotating blades are coupled to a rotatable member, such as a rotor. At least some known stationary nozzles include a plurality of airfoils and/or dovetailed end portions that channel the steam flow downstream. Each nozzle, in conjunction with an associated row of rotating blades, is sometimes referred to as a turbine stage and most known steam turbine engines include a plurality of stages.
Known steam turbine engines may include an annular outer ring or blinglet ring that substantially circumscribes the rotor. The outer ring has a predefined shape and may include at least one groove that receives, for example, at least one stationary nozzle therein. Having the nozzle coupled within the groove of the outer ring enables the nozzle to remain stationary during turbine engine operation. As steam flows through each stage, the pressure drops and various forces are applied to each nozzle and rotating blade. When forces, such as radial forces, are applied to the dovetail portion of a stationary nozzle, the forces are induced to the outer ring. Such forces, along with the substantially high temperatures of the steam flow may distort the outer ring. For example, over time, the outer ring may bend or even break. As a result, the nozzle may detach from the outer ring. When the nozzle is detached from the outer ring, the nozzle may move, for example, as the rotor rotates. Continued operation of a steam turbine engine with a damaged outer ring and/or a detached nozzle may cause damage to other components and/or may lead to a premature failure of the steam turbine engine.
To prevent distortion of the outer ring, some known steam turbine engines have been modified. For example, relatively thicker outer rings may be used with the same known steam turbine engines. As steam flows through each stage of such turbine engines, the relatively thicker outer ring may be able to withstand the forces and the flow temperatures. As such, distortion of the predefined shape of the outer ring may be prevented and the nozzle may remain coupled to the outer ring. However, manufacturing relatively thicker outer rings can be expensive and time-consuming, as additional materials are required.